This invention relates generally to measuring methods and apparatus for measuring, and is more particularly directed to the measurement of the relative amounts of a first and second liquid, where one liquid is held up or suspended in a liquid/liquid dispersed phase system. The invention is directed more specifically to a system in which the travel time of ultrasonic pulses through the liquid/liquid dispersion is employed to derive the fractional volumetric dispersed phase holdup of the two-liquid dispersed phase system.
Previously, the measurement of the dispersed phase fractional volumetric holdup in two-phase liquid systems has been attempted by such techniques as displacement, pressure differentials, direct sampling, light beam attenuation, and electroresistivity. While these approaches can be employed to derive a result, none of them permits estimation or monitoring of the dispersed phase fractional volumetric holdup under steady state process conditions or during transient conditions. Consequently, none has proved entirely effective for monitoring the dispersed phase fractional volumetric holdup for liquids within a reaction vessel.
The dispersed phase fractional holdup is an important measure of the efficacy of a chemical reaction betweem two liquids, as it corresponds to the relative mass transfer area of one liquid to the other. Consequently, real-time accurate knowledge of this quantity permits optimization of liquid flow rates to carry out the chemical reaction with minimal waste and consistent product.
One previous approach to ultrasonic measurement of this quantity employed a sound velocimeter that was immersed in the liquid/liquid dispersion. This technique had the drawback of interfering with the flow of liquids through the reactor vessel.